1. Field of the Invention
The present invention relates to an apparatus for conveying a workpiece from a press machine to another press machine.
2. Description of The Related Art
Generally speaking, in a pressing process, workpieces are successively subject to drawing, blank piercing, piercing and bending etc. by a plurality of press machines to produce complete products. Accordingly, it is necessary to convey the workpieces (halfproducts) from a press machine to a subsequent press machine.
There are many known conveying apparatuses for automatically conveying the workpieces between the press machines. It is often necessary to turn the workpieces upside down when they are conveyed from one press machine to a subsequent press machine. Accordingly, the conveying apparatus usually has a station in which workpieces which are discharged from a die frame of a press machine by means of an unloader are received, a station in which the workpieces received by the receiving station are turned upside down, a station in which the turned workpieces are conveyed, and a station in which the conveyed workpieces are transferred to another unloader. Each station needs a workpiece receiver etc.
In a known conveying apparatus in which a workpiece is located on a workpiece receiver or a carriage, the operations at the respective stations are individually effected in a stepped fashion, resulting in a long time needed to carry the workpieces. In addition to the foregoing, since each station has a tool, such as a workpiece receiver, it is necessary to exchange the tools of all of the stations in order to convey different types of workpieces, resulting in an increased amount of labor and time for the exchange operation.
To solve the problem mentioned above, there is also known a workpiece conveying apparatus which has clamps holding the workpieces, so that the workpieces are turned upside down and conveyed by the clamps. However, in this type of conveying apparatus, since the clamp is usually actuated by a hydraulic cylinder device, a pressurized fluid source for working the cylinder device, conduits for connecting the cylinder device to the pressurized fluid source, valves for controlling the fluid connection, and conductive cables or the like connected to the cylinder device are needed.
These conduits and the cables are moved together with the operation of the cylinder device, so that legs of an operator or another machine may be caught by the conduits or the cables, which is dangerous. Furthermore, when the conduits or the cables catch operator's legs or another machine, the conduits or the cables can be cracked or partially broken, resulting in a leakage of the fluid.